Conventionally, as an actuation member of a linear actuator or an actuation member of a valve, a laminated piezoelectric actuator formed by laminating piezoelectric elements has often been used, and flow controllers that control the flow with a piezoelectrically actuated valve using a laminated piezoelectric actuator are also known.
As an example of a flow controller of this type, a flow controller 30 shown in FIG. 23 is configured such that a valve element 33, such as a metal diaphragm valve, interposed in a flow channel 32 inside a body 31 can be operated to open and close with a laminated piezoelectric actuator 34 attached to the body 31 (Patent Documents 1 to 3, etc.).
The flow controller 30 shown in FIG. 23 is called a pressure-type flow controller. When a so-called critical expansion condition of (P1/P2)≥about 2 is maintained between the pressure P2 on the downstream side and the pressure P1 on the upstream side of an orifice 35 interposed in the flow channel 32, the gas flow rate Q through the orifice 35 is represented by Q=KP1 (wherein K is a constant).
Utilizing this relation, the upstream-side pressure P1 detected by a pressure detector 36 is feedback-controlled using the valve on the upstream side, whereby the flow rate Q can be controlled with high accuracy. Further, excellent characteristics can be exerted in that even when there is a significant change in the pressure of the gas on the upstream side of the valve element 33, the controlled flow value hardly changes. The highly accurate control of the upstream-side pressure P1 can be achieved by a piezoelectrically actuated valve using the laminated piezoelectric actuator 34, which has excellent responsiveness.